Spatio-temporal dynamics of perennial energy crops in the U.S. Midwest agricultural lands

Transcription

1 Spatio-temporal dynamics of perennial energy crops in the U.S. Midwest agricultural lands Cuizhen (Susan) Wang Associate Professor, Dept. of Geography, University of Missouri Tel: with co-authors Gary Stacey, Center for Sustainable Energy, MU Felix B. Fritschi, Division of Plant Sciences, MU Wyatt Thompson, FAPRI, and Dept. of Agricultural/Applied Economics, MU Timothy C. Matisziw, Dept. of Geography, Dept. of Civil/Environmental Engineering, MU Zhengwei Yang, USDA/NASS 1 / 18

2 Introduction Biomass exceeds 3% of energy supplies and is the largest source of renewable energy in the United States; Upon an optimistic estimate, biomass feedstocks could replace 30% of domestic petroleum consumption by 2030 (Perlack et al. 2005); Corn ethanol currently constitutes 99% of US biofuel (Farrel et al. 2006). The US biofuel refiners budgeted 4.2 billion bushels of corn (1/3 of US corn production) in the marketing year (Economic Research Service 2010). Environmental Ecological socio-economic concerns 2 / 18

3 Native prairie grasses are identified by DOE as a model cellulosic crop, an alternative of bioenergy feedstock. Warm-season native grasses currently grow in mixed conditions with cool-season forage grasses, and have not been mapped in any published agricultural databases. Current spatial distributions and temporal dynamics? 3 / 18 (Source: Oak Ridge National Lab)

4 Study area and data sets The Midwest agricultural region Validation sites: Flint Hills, KS The largest unplowed tallgrass prairie remn. (>80% native grasses). Cherokee Plain, MO Sandhills upland prairie, NE 4 / 18

5 Satellite imagery and published maps 500-m, 8-day MODIS surface reflectance products (MOD09A1); - 4 scenes; -NDVI time series (46 scenes/year) - 10-year period (00-09); Cropland Data Layers (CDL) - USDA NASS - 12 states Major crops in the Great Plains - Grass (tall/short/cool-season); - Corn+Soybean; - Winter wheat - Spring wheat 5 / 16

6 Time series analysis Approach median filter spikes removal Savitzky-Golay filter curve smoothing Asymmetric Gaussian simulation extracting phenology matrices Source: Jonsson and Eklundh TIMESAT 6 / 18

7 Example time series: (Source: Wang et al. 2011) Corn Soybean Winter wheat WSG grass CGS grass 7 / 35 7 / 18

8 Phenology metrics TIMESAT extracted (3 out of 11): End of season: when NDVI decrease to 20% of amplitude; Growing length: number of dates in start-end of seasons; Cumulative growth ( NDVI):NDVI integral in start-end of seasons; Self-identified: peak date: dates of peak NDVI; - Early: peak date falls in DOY (Jan Mid June) - Middle: peak date falls in DOY (May - Mid July) - Late: peak date falls in DOY (Mid June Mid Nov) Summer dry-down ( NDVI): decrease of NDVI in spring-summer if peak NDVI falls in early stage (especially useful for winter wheat); 8 / 18

9 Longitudal shifts Peak Date: (2days/degree) Source: Wang et al / 18

10 Peak NDVI Seaon Length Peak NDVI End Date Climate-induced shifts Peak_date End_date Peak_NDVI Season Length / 18

11 Phenology metrics inventory (CART results) PDatww Lencorn_ sw Endsw Lentallgra ss PVALww _sw PVALtall grass / 18

12 Phenology-based decision tree (concept framework) Peak in early spr. W. wheat; CSG Summer drydown Y W. wheat Time series Short grow season Corn/Soy; S. wheat; Short grs Early end Y S. wheat Late peak date Y Corn/Soy Long grow season WSG; CSG Low peak value Y Short grs Shorter season Y WSG CSG

13 (thresholds flowchart) For more details, please refer to Wang et al., Annuals of AAG, 101(4), / 18

14 Results The Midwest crop maps, / 15

15 Flint Hill, KS ( ) 15 / 16

16 Cherokee Plain, MO (with past studies) DOY Date Sensor 52 2/21/2007 ASTER 73 3/14/2006 TM 92 4/2/2007 TM A 2-year MDC project 106 4/16/2007 AWIFS (A) 111 4/21/2007 AWIFS (A) 134 5/14/2007 AWIFS (B) 140 5/20/2007 AWIFS (A) /02/2006 TM /21/2007 TM /07/2007 AWIFS (A) 192 7/11/2007 AWIFS (B) 202 7/21/2007 ASTER 220 8/8/2007 TM 228 8/16/2007 ASTER 240 8/28/2007 AWIFS (B) 271 9/27/2008 TM /19/2007 ASTER /29/2008 TM /9/2006 TM Pr. State Park Osage Pr.. Taberville Pr. WKT Pr. 16 / 16

17 Summary and future research Native warm-season grasses in the Midwest hold unique phenology metrics (time series analysis); Phenology metrics vary with inter-annual climate dynamics (phenology metrics inventory); The 20+ million ha of native grasses (upon validation) in the Midwest indicates its high bioenergy potential; The spatially explicit energy crop map is a quantitative supplement to county-level biomass supplies. Next? Future investigation: region-wide validation! biomass quant. of energy crops; Bioenergy policy and LULC. ORNL Switchgrass production. 17 / 18

18 Thanks! Acknowledgement: This research is supported by the Mizzou Advantage Project. We would like to thank Le T. Ngan, Wei Zhang, Qing Chang in Dept. of Geography and D.J. Donahue at FAPRI in data process. Also our thanks to USDA/NASS for providing the CDL data that serve as excellent reference in this research. 18 / 18